Keele Campus Storm Drainage. Presented by Mark Hagesteijn September 24, 2013

Transcription

1 Keele Campus Storm Drainage Presented by Mark Hagesteijn September 24,

2 Presentation Overview Urbanization Impact on the Hydrologic Cycle Why Do We Manage Stormwater? Typical Stormwater Management (SWM) Practices Keele Campus Storm Drainage History City of Toronto SWM Design Criteria SWM criteria for Keele Campus Building Sites Maintenance of SWM Facilities 2

3 Urbanization Impact on the Hydrologic Cycle 3

4 Urbanization Impact on Hydrologic Cycle The Natural Hydrologic Cycle Consists Generally of: Precipitation Evaporation & evapotranspiration Infiltration Surface runoff 4

5 Urbanization Impact on Hydrologic Cycle Figure from MOE Publication Understanding Stormwater Management: An Introduction to Stormwater Management Planning & Design 5

6 Urbanization Impact on Hydrologic Cycle Impacts of Urbanization: Increased impervious (hard) surfaces Decreased pervious (soft) surfaces 6

7 Urbanization Impact on Hydrologic Cycle Figure 2 from MOE Publication Understanding Stormwater Management: An Introduction to Stormwater Management Planning & Design 7

8 Urbanization Impact on Hydrologic Cycle Results: Increase in runoff peak flows Increase in runoff volume Increase in watercourse erosion Increase temperature of runoff Increase in sedimentation Increase in pollutants into water bodies (sanding & salting, vehicle pollution, litter, pet wastes, pesticides, herbicides and fertilizers Decrease in groundwater recharge Decrease in evaporation & evapotranspiration 8

9 Urbanization Impact on Hydrologic Cycle Increased runoff volumes and peak flows result in undesirable flooding Image Sources: / / 9

10 Urbanization Impact on Hydrologic Cycle Increased runoff volumes and peak flows result in undesirable stream erosion Figures from MOE Publication Understanding Stormwater Management : An Introduction to Stormwater Management Planning & Design 10

11 Urbanization Impact on Hydrologic Cycle Increased runoff temperature, sediments & pollutants result in beach closures 11

12 Urbanization Impact on Hydrologic Cycle Decreased infiltration results in loss of base flow and resulting vegetation 12 Image source:

13 Why Do We Manage Stormwater? 13

14 Why Do We Manage Stormwater? Why Manage Stormwater: Protect against flooding Protect against watercourse erosion Protect receiving water quality Maintain water balance & baseflow How to Manage Stormwater: Strive to maintain or mimic the natural hydrologic cycle 14

15 Why Do We Manage Stormwater? Urban vs. Rural Runoff Characteristics Figure from MOE Stormwater Management Planning & Design Manual March

16 Typical SWM Practices 16

17 Typical SWM Practices Water Quantity (volume control): Runoff Volume reduction can be achieved by implementing one or more of the following: landscaping (i.e. infiltration & evapotranspiration) infiltration facilities green roofs rainwater harvesting 17

18 Typical SWM Practices Water Quantity (volume control) (cont.): Infiltration - Reduce Lot Grading of Landscaped Areas Figures From MOE Stormwater Management Planning & Design Manual March

19 Typical SWM Practices Water Quantity (volume control) (cont.): Infiltration - Roof Leader to soakaway pit 19 Figure from MOE Publication Understanding Stormwater Management: An Introduction to Stormwater Management Planning & Design

20 Typical SWM Practices Water Quantity (volume control) (cont.): Infiltration - Infiltration Trench (by Stormtech) Images obtained from Stormtech Website 20

21 Typical SWM Practices Water Quantity (volume control) (cont.): Infiltration - Pervious Catchbasin Figures From MOE Stormwater Management Planning & Design Manual March

22 Typical SWM Practices Water Quantity (volume control) (cont.): Infiltration - Permeable Pavement concrete unit pavers asphalt 22

23 Typical SWM Practices Water Quantity (volume control) (cont.): Green Roofs or Rooftop Gardens Source: Great Lake Water Institute 23

24 Typical SWM Practices Water Quantity (volume control) (cont.): Rainwater harvesting 24

25 Typical SWM Practices Water Quantity (rate control): Runoff Rate reduction can be achieved by implementing one or more of the following: landscaping (i.e. infiltration & evapotranspiration) infiltration facilities green roofs rainwater harvesting storage facilities (such as rooftop storage, parking lot storage, and storage in pipes, tanks and ponds) 25

26 Typical SWM Practices Water Quantity (rate control) (cont.): Rooftop storage Figures from Zurn Control Flo Brochure 26

27 Typical SWM Practices Water Quantity (rate control) (cont.): Parking Lot Storage Figures from ICDS for Stormwater Systems Brochure 27

28 Typical SWM Practices Water Quantity (rate control) cont..): Wet Pond Figure from MOE Stormwater Management Planning & Design Manual March

29 Typical SWM Practices Water Quantity (rate control) (cont.): Dry Pond Figure from MOE Stormwater Management Planning & Design Manual March

30 Typical SWM Practices Water Quality (TSS control): TSS removal can be achieved by implementing one or more of the following: landscaping (i.e. filter strips) permeable pavement infiltration facilities ponds (drain 25mm storm over 24 to 48hr duration) grass swales (25mm storm with V < 0.5 m/s) oil-grit separators filters 30

31 Typical SWM Practices Water Quality (TSS control) (cont.): Oil/Grit Separator (Stormceptor by Imbrium) 31 Image obtained from

32 Typical SWM Practices Water Quality (TSS control) (cont.): Filters (Jellyfish Filter) Image obtained from

33 Keele Campus Storm Drainage History 33

34 Keele Campus Storm Drainage History 34 34

35 Keele Campus Storm Drainage History 35 35

36 Keele Campus Storm Drainage History 36 36

37 Keele Campus Storm Drainage History 37 37

38 Keele Campus Storm Drainage History 38 38

39 Keele Campus Storm Drainage History 39 39

40 Keele Campus Storm Drainage History 40 40

41 City of Toronto SWM Design Criteria In 2006, the City developed a set of Management Guidelines to support the implementation of the WWFMP and Policy Provides technical requirements for all new developments Effective July 1,

42 Toronto WWFM Guidelines City of Toronto SWM Criteria Three Primary Focuses: Water Quantity peak runoff flow controls for flood management and to mitigate erosion impacts Water Quality for protection of downstream resources Water Balance runoff volume controls to reduce impact on infrastructure, erosion control, groundwater recharge and habitat protection 42

43 Toronto WWFM Guidelines City of Toronto SWM Criteria 43

44 Toronto WWFM Guidelines City of Toronto SWM Criteria 44

45 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites The Tennis Canada Pond and Stong Pond provide water quantity (i.e. peak flow and erosion controls) and water quality control for the Keele Campus draining to the Hoover Creek in accordance with the City s WWFM Guidelines, as demonstrated in the following reports: Hoover Creek Watershed Stormwater management Plan, York University, Keele Campus of April 5, Stong Pond Improvements, York University Keele Campus of June 12,

46 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites To maintain the performance of the existing SWM ponds, without enlarging the existing ponds and storm sewers, the following is required: Maintain the existing peak discharge flows and runoff volumes from the building sites for the 25mm storm event to the 100 year storm event. Maintain the existing drainage pattern where possible (i.e. use the existing drainage outlets at each site). 46

47 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites Water Balance (i.e. volume control) Retain stormwater on-site to achieve the same level of annual volume of runoff from the site under pre-development (i.e. existing) conditions during the 25mm storm event to the 100 year storm event (i.e. maintain existing percentage of imperviousness). 47

48 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites Water Quality TSS removal remove 80% of the Total Suspended Solids (TSS) on an annual loading basis from pavement which is in addition to the existing pavement on the site. Disinfection of the runoff is not required, because the runoff does not discharge directly into Lake Ontario. 48

49 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites Peak Runoff Flow Control Control the post-development peak runoff flows to the pre-development peak runoff flows or less during the 4 hour 25mm storm event, and 6 hour 2yr, 5yr and 100 yr AES storm events. For sites which drain into municipal storm sewers on The Pond Road, Sentinel Road and Murray Ross Parkway (at CanLan), the allowable discharge rate into the municipal sewer must also be equal or less to the 2 yr storm peak runoff flow based on a runoff coefficient of 0.5 and the City of Toronto 2 yr storm rainfall intensity. 49

50 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites Peak Runoff Flow Control (continues) The on-site minor system shall convey the post development peak runoff flow from the 2 yr storm event and the major system shall convey the post development runoff of the 100 yr storm event using the following City of Toronto rainfall intensities: I 2yr = 21.8/(T) 0.78 (mm/hr) I 100yr = 59.7/(T) 0.80 (mm/hr) 50

51 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites Erosion Control The erosion control criteria is satisfied when the water balance and peak runoff flow criteria have been implemented. 51

52 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites New Connection to Municipal Storm Sewer This criteria only applies to sites which drain to municipal sewers. Sewer connections to a municipal storm sewer are not permitted unless it can be demonstrated with a SWM report that there is no practical alternative of draining the site. 52

53 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites Downspout Connection to Municipal Storm Sewer This criteria only applies to sites which drain to municipal storm sewers. Downspouts shall be directed to pervious areas for infiltration or other areas for re-use (i.e. cisterns), unless this would create a hazardous condition or is technically not feasible then the downspouts could be connected to the municipal sewer. 53

54 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites Foundation Drain Connection to Municipal Storm Sewer This criteria only applies to sites which drain to municipal storm sewers. Foundation Drains shall be pumped to grade to pervious areas for infiltration or other areas for reuse (i.e. cisterns), unless this would create a hazardous condition or is technically not feasible then the foundation drains could be connected to the municipal sewer. 54

55 Toronto WWFM Guidelines SWM Criteria for Keele Campus Building Sites Erosion Control during Construction Provide temporary erosion and sediment controls in accordance with the GTA CA's Erosion & Sediment Control Guidelines for Urban Construction (2006). 55

56 Maintenance of SWM Facilities The storm drainage systems must be maintained at regular intervals by inspecting and cleaning the following: Impermeable Pavements - Sweep in spring to remove sand from de-icing operation Permeable pavers Vacuum clean pavement grooves in spring and fall Catchbasins Vacuum clean sump yearly Oil/grit separator manhole -Vacuum clean sump as required Cistern Vacuum clean sump as required Manhole with flow control - Vacuum clean sump as required Green Roofs Remove weeds as required Roof flow controls Remove debris as required Ponds Dredge or Vacuum clean forebays as required Sewers Flush as required

57 Questions? 57